RT Journal Article
T1 Geología de las ultramafitas pre-andinas de Tapo y Acobamba, Tarma, Cordillera Oriental del Perú
T1 Geology of the Tapo and Acobamba pre-andean ultramafites, Tarma, Cordillera Oriental, Perú
A1 Castroviejo, Ricardo
A1 Feliciano Rodrigues, José
A1 Acosta, Jorge
A1 Pereira, Eurico
A1 Romero, Darwin
A1 Quispe, Jorge
A1 Espí, José Antonio
AB Ultramafic rocks occur scattered along a 300 km long NNW-SSE trending belt, parallel to the centralPeruvian Andes in the Cordillera Oriental, from Tarma (Junín Dept.) to Huancapallac and Tingo María(Huánuco Dept.). The Tarma occurrences (Tapo and Acobamba) are dealt with here, as the first step of abroader research. The Tapo massif comprises strongly tectonised serpentinites with scarce peridotitic relics,amphibolites and podiform chromitites. It was overthrust on early Carboniferous metasedimentary rocksof the Andean basement (Ambo Group), and it shows evidences of a pre-Andean deformational history,not observed in the Ambo Group; the basal thrust plane is folded by the Andean tectonics. The twosmaller Acobamba occurrences are also allochtonous and show similar tectonic features. Major and traceelement composition of amphibolites point to a tholeiitic basalt (to picrobasalt) protolith, compatiblewith an ocean-ridge or ocean-island environment. Small podiform chromitite lenses and chromitedisseminations also occur; they are strongly deformed, metamorphosed and overprinted by hydrothermalalteration related to deformation, and were the subject of small scale mining. The ores comprise mainlychromite, ferritchromite, spinel, magnetite, ilmenite and scarce sulphides, as well as the secondary mineralsstichtite and nimite. Results of this work exclude current interpretations of the Tarma ultramafites asautochtonous igneous intrusives, and point to a new interpretation for their emplacement
YR 2009
FD 2009
LK http://hdl.handle.net/10272/8046
UL http://hdl.handle.net/10272/8046
LA spa
DS Repositorio Institucional de la Universidad de Huelva
RD 31 may 2026